Acta physiologica Scandinavica
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Acta Physiol. Scand. · Aug 1999
Clinical TrialHyperoxia does not increase peak muscle oxygen uptake in small muscle group exercise.
We examined the influence of hyperoxia on peak oxygen uptake (VO2peak) and peripheral gas exchange during exercise with the quadriceps femoris muscle. Young, trained men (n=5) and women (n=3) performed single-leg knee-extension exercise at 70% and 100% of maximum while inspiring normal air (NOX) or 60% O2 (HiOX). Blood was sampled from the femoral vein of the exercising limb and from the contralateral artery. ⋯ The VO2peak-to-PvO2 ratio was lower (P < 0.05) in HiOX than in NOX suggesting a lower O2 conductance. We conclude that the similar VO2peak values despite higher O2 driving pressure in HiOX indicates a peripheral limitation for VO2peak. This may relate to saturation of the rate of O2 turnover in the mitochondria during exercise with a small muscle group but can also be caused by tissue diffusion limitation related to lower O2 conductance.